Abstract: A display may be based on a display unit that is mounted within a chassis. The display unit may be a liquid crystal display unit. A backlight may be used to illuminate the display unit. The backlight may include a light guide plate. Light from a light source may be launched into an edge of the light guide plate. Scattered light from the light guide plate may travel vertically along a vertical axis that is perpendicular to the plane that contains the light guide plate. The scattered light may pass through the display unit and may serve as backlight for the display. The light guide plate may be mounted within a rectangular opening in the chassis. The edges of the rectangular opening and the edges of the light guide plate may be configured to reduce excessive reflections. These edges may have reflection-reducing coatings, non-planar surfaces, and other reflection-reducing configurations.

Abstract: Personalization images are included in email messages to combat phishing attacks in which an attacker attempts to trick a user into divulging sensitive information over the Internet. When a recipient of an email message receives a message, the recipient can visually inspect the personalization image in the message. If the personalization image is missing or if the personalization image is not valid, the email recipient is alerted to the possibility of a phishing attack. Email message content may be encrypted. A gateway associated with an email message sender may be used to perform encryption operations on the message content. The gateway may create an html version of the email by placing the encrypted message content in an html wrapper. An image reference corresponding to the personalization image may be embedded in the html version of the message.

Abstract: Portable electronic devices are provided with wireless circuitry that includes antennas and antenna isolation elements. The antennas may include antennas that have multiple arms and that are configured to handle communications in multiple frequency bands. The antennas may also include one or more antennas that are configured to handle communications in a single frequency band. The antennas may be coupled to different radio-frequency transceivers. For example, there may be first, second, and third antennas and first and second transceivers. The first and third antennas may be coupled to the first transceiver and the second antenna may be coupled to the second transceiver. The antenna isolation elements may be interposed between the antennas and may serve to reduce radio-frequency interference between the antennas. There may be a first antenna isolation element between the first and second antennas and a second antenna isolation element between the second and third antennas.

Abstract: Portable computer structures are provided. The portable computer structures may include connector structures. The portable computer may have a case. A portion of the connector structure may be formed by the case of the portable computer. The portable computer may have a circuit board with grounding spring-loaded pins which electrically ground the circuit board to the case of the portable computer. The portable computer may have an optical disk drive that is form fitted to mount to the portable computer case.

Abstract: Asymmetric transistors such as asymmetric pass transistors may be formed on an integrated circuit. The asymmetric transistors may have gate structures. Symmetric pocket implants may be formed in source-drains on opposing sides of each transistor gate structure. Selective heating may be used to asymmetrically diffuse the implants. Selective heating may be implemented by patterning the gate structures on a semiconductor substrate so that the spacing between adjacent gate structures varies. A given gate structure may be located between first and second adjacent gate structures spaced at different respective distances from the given gate structure. A larger gate structure spacing leads to a greater substrate temperature rise than a smaller gate structure spacing. The pocket implant diffuses more in portions of the substrate with the greater temperature rise, producing asymmetric transistors.

Abstract: Integrated circuits with stressed transistors are provided. Stressing transistors may increase transistor threshold voltage without the need to increase channel doping. Stressing transistors may reduce total leakage currents. It may be desirable to compressively stress N-channel metal-oxide-semiconductor (NMOS) transistors and tensilely stress P-channel metal-oxide-semiconductor (PMOS) transistors to reduce leakage currents. Techniques that can be used to alter the amount of stressed experienced by transistors may include forming a stress-inducing layer, forming a stress liner, forming diffusion active regions using silicon germanium, silicon carbon, or standard silicon, implementing transistors in single-finger instead of multi-finger configurations, and implanting particles. Any combination of these techniques may be used to provide appropriate amounts of stress to increase the performance or decrease the total leakage current of a transistor.

Abstract: Handheld electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures. An antenna may be located in an upper right corner of the handheld device as the handheld device is operated in a portrait mode. When the handheld device is rotated counterclockwise and operated in a landscape mode, the antenna is located in an unobstructed upper left corner of the device. The antenna may be formed from a strip of conductor. A proximal end of the strip of conductor may be connected to a transmission line. A distal end of the strip of conductor may be routed away from housing surfaces by bends formed in the strip. A printed circuit board in the handheld electronic device may have a hole. The distal end of the strip of conductor may be located adjacent to the hole.

Abstract: A portable computer is provided that has a housing. Upper and lower portions of the housing may be joined using a hinge. A clutch mechanism may be associated with the hinge. The clutch mechanism may exhibit asymmetrical friction during opening and closing of the portable computer housing portions. Additional closing force may help to prevent the computer from having a lid that is too easy to close, without overwhelming the clutch with unnecessary friction. The clutch may have a clutch spring that is attached to a clutch shaft using a slot in the shaft. A lobe may be provided in the spring in the vicinity of the slot. A protective cap may be provided over the tip of the shaft to prevent damage to nearby wires. A friction band in the clutch may be used to directly engage an end of the spring.

Abstract: Electronic devices and equipment may communicate over a wired communications path. The wired communications path may include one or more wires and may be associated with a headphone cable. Data may be conveyed in the form of a digital data stream containing multiple traffic channels. The digital data stream may include superframes, each of which has multiple frames of data. The frames of data may each contain a number of data slots. Some of the slots in a superframe may be used exclusively by a particular one of the traffic channels. Boundary slots may be shared between traffic channels. Data interface circuitry may implement a data dispersion algorithm that determines the pattern in which data from each traffic channel is distributed within each boundary slot. Transmitting data interface circuitry may merge traffic channels into a single data stream. Receiving data interface circuitry may reconstruct the traffic channels.

Abstract: Configurable phase-locked loop circuitry is provided. The phase-locked loop circuitry may include a buffer having a buffer output and a multiplexer having inputs and an output. The phase-locked loop circuitry may include multiple voltage-controlled oscillators. The phase-locked loop circuitry may be configured to switch a desired one of the voltage-controlled oscillators into use. Each voltage-controlled oscillator may be controlled by control signals applied to a control input for that voltage-controlled oscillator. The control input of each voltage-controlled oscillator may be connected to the buffer output. The output of each voltage-controlled oscillator may be connected to a respective one of the multiplexer inputs. Power-down transistors may be used to disable unused voltage-controlled oscillators to conserve power. The power-down transistors and the multiplexer may be controlled by signals from programmable elements.

Abstract: An electronic device such as a handheld electronic device may include wireless communications circuitry. The wireless communications circuitry may include a radio-frequency receiver circuit or other circuitry that is sensitive to noise. Audio amplifier circuitry may be provided in the electronic device to amplify audio signals for a speaker. The audio amplifier circuitry may include class AB amplifier circuitry for operating in a low noise mode and class D amplifier circuitry for operating in a low power mode. The audio amplifier circuitry may include a control input path that receives control signals in real time. When it is determined that the wireless receiver or other sensitive circuit is active, the audio amplifier can be configured to operate in its low noise mode using the class AB amplifier. When it is determine that the wireless receiver is not being used, the class D circuitry may be switched into use to conserve power.

Abstract: An image sensor has an array of pixels of different colors. The pixels may be arranged in a repeating pattern of eight pixels having four rows and two columns. During charge summing operations, the first and third rows may share a floating diffusion and the second and fourth rows may share a floating diffusion. When charge summing is inactive, transfer gates in the first and second columns may be controlled independently, while transfer gates in pairs of rows may be controlled simultaneously. When charge summing is active, summed charges from pixels of the same color in the first and third rows may be placed on the floating diffusion shared by the first and third rows and summed charges from pixels of the same color in the second and fourth rows may be placed on the floating diffusion shared by the second and fourth rows.

Abstract: A portable computer may include battery indicator light structures. Battery status information in the portable computer may be presented to a user using an array of light-emitting diodes or other light emitters. Light-emitting diodes may be mounted on a printed circuit board. A stiffener may provide the printed circuit board with rigidity. The printed circuit board may include a connector that allows the board to be connected to a main logic board. A switch on the printed circuit board may be actuated by a power button on the portable computer. An opaque member with an array of holes may be used to reduce light bleed between adjacent light-emitting diodes. Diffusing plastic may be mounted within the array of holes. Bumps in the diffusing plastic may mate with corresponding holes on a portable computer housing.

Abstract: Antennas for electronic devices such as portable computers are provided. An antenna may be formed from a conductive cavity and an antenna probe that serves as an antenna feed. The conductive cavity may have the shape of a quartered rectangular cavity and may have first and second side walls, top and bottom walls, and first and second openings. The first and second openings may be planar in shape and may meet at a right angle along an axis. The antenna probe may be disposed along the axis. The axis at which the first and second openings of the cavity meet may be located at the corner of an electronic device housing. The portable computer may have upper and lower housing portions that meet at a gasket. The gasket may be placed adjacent to the cavity face openings so that radio-frequency signals may enter and exit the cavity through the gasket.

Abstract: A charge pump circuit is provided that has a controllable ramp rate. The charge pump circuit may receive a control signal from a control circuit. The control signal may be asserted by the control circuit to turn on the charge pump circuit. When the charge pump circuit is turned on, the charge pump circuit produces an output voltage. The output voltage ramps up from an initial value to a desired target value. During the ramp up process, a ramp rate regulation circuit monitors the output voltage and ensures that the ramp rate does not exceed a desired maximum value. A capacitor may be charged at a desired ramp rate to use as a time-varying reference voltage. A feedback circuit may be used to maintain the output voltage at the desired target value once the ramp-up process is complete.

Abstract: Configurable time-borrowing flip-flops may be based on configurable pulse generation circuitry and pulse latches. The circuitry may use a self-timed architecture that controls the width of clock pulses that are generated so that the pulse latches that are controlled by the clock pulses exhibit a reduced risk of race through conditions. Latch circuitry may be provided that is based on a pulse latch and an additional latch connected in series with the pulse latch. In situations in which there is a potential for race through conditions on an integrated circuit, the additional latch may be switched into use to convert the latch circuitry into an edge-triggered flip flop. Clock trees may be provide with configurable shorting structures that help to reduce clock skew. Low-contention clock drivers may drive signals onto the clock tree paths.

Abstract: Nonvolatile memory element circuitry is provided that is based on metal-oxide-semiconductor transistor structures. A nonvolatile memory element may be based on a metal-oxide-semiconductor transistor structure that has a gate, a drain, a source, and a body. During programming operations, control circuitry floats the body while applying a positive voltage to the drain and a negative voltage to the source. This causes the drain and source, which serve as the collector and emitter in a parasitic bipolar transistor, to break down. The drain-to-source (collector-to-emitter) breakdown causes sufficient current to flow through the source to alter the source electrode and thereby increase the resistance of the source significantly. During sensing operations, control circuitry may apply a voltage across the drain and source while grounding the body to determine whether the memory element has been programmed.

Abstract: Portable electronic devices are provided that contain radio-frequency transceiver circuitry. Power amplifier circuitry may amplify transmitted radio-frequency signals from the radio-frequency transceiver circuitry. The power amplifier circuitry may be powered with a power supply voltage. The power supply voltage may be reduced to conserve power provided that requirements such as adjacent channel leakage ratio requirements are satisfied. Calibration measurements may be made to determine the extent to which power can be conserved by power supply voltage reductions. During calibration, the transceiver circuitry may transmit signals in a transmit subband. Test equipment that is external to the device may frequency shift the transmitted signals into a receive subband. The frequency-shifted signals may be fed back into the device. The transceiver circuitry in the device may make power measurements on the fed back signals. The power measurements may be used to compute adjacent channel leakage ratio values.

Abstract: Hardened programmable logic devices are provided with programmable circuitry. The programmable circuitry may be hardwired to implement a custom logic circuit. Generic fabrication masks may be used to form the programmable circuitry and may be used in manufacturing a product family of hardened programmable logic devices, each of which may implement a different custom logic circuit. Custom fabrication masks may be used to hardwire the programmable circuitry to implement a specific custom logic circuit. The programmable circuitry may be hardwired in such a way that signal timing characteristics of a hardened programmable logic device that implements a custom logic circuit may match the signal timing characteristics of a programmable logic device that implements the same custom logic circuit using configuration data.

Abstract: A portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and an inverted-F antenna structure. The slot antenna portion of the hybrid antenna may be used to provide antenna coverage in a first communications band and the inverted-F antenna portion of the hybrid antenna may be used to provide antenna coverage in a second communications band. The second communications band need not be harmonically related to the first communications band. The electronic device may be formed from two portions. One portion may contain conductive structures that define the shape of the antenna slot. One or more dielectric-filled gaps in the slot may be bridged using conductive structures on another portion of the electronic device. A conductive trim member may be inserted into an antenna slot to trim the resonant frequency of the slot antenna portion of the hybrid antenna.